Nuclear medicine is a branch of medicine in which radioisotopes are administered for the diagnostic and therapeutic purposes in various disorders of the human body. In nuclear medicine, clinical information is derived from observing the distribution of a pharmaceutical administered to the patient. By incorporating a radionuclide into the pharmaceutical, measurements can be made of the distribution of this radiopharmaceutical by noting the amount of radioactivity present.

The most common type of imaging procedure is in-vivo [Latin for ‘within the living’], using a gamma camera which measures the gamma rays emitted by the radionuclides administered in the body.

The short half-life and permissible small doses of radioactivity administered have the least hazards of radiation to the body, and with side effects that are relatively very rare. The best part of nuclear medicine is that it does physiological studies of the body without any direct physical intervention.

The imaging technique reveals the body’s biochemistry depending upon the choice of radiopharmaceutical used. This is in contrast to other types of imaging in radiology. For example, X-rays, ultrasonography, or MRI & CT scanners which reveal the anatomy of the body.

To measure very low amounts of radioactivity, high sensitivity, whole-body counters with heavily shielded probe detectors are used. In-vitro[Latin for ‘within glass’] studies are done with samples taken from the patient - breath, blood, urine and faeces samples may be used to find the amount of radiopharmaceutical present. These studies are done with gamma & beta counters.

Since the diagnostic information is provided by the action of the pharmaceutical, the role of the radioactivity is a purely passive one, enabling the radiopharmaceutical to be localized.

The PET [positron emission tomography] scanner provides molecular imaging of the biology of normal cellular function and its transformation to disease in a living subject. This is done by selecting targets of normal tissue and disease of biochemical processes of interest and labeling a molecular probe selective for the target with a positron emitting radionuclide. For example, fluorine-18, carbon-11, nitrogen-13, oxygen-15, etc.

With the emergence of PET/CT hybrid scanners in 1998 and the recent innovation of PET/MRI hybrid scanners, we can do both molecular and anatomical imaging of a patient with the same camera. It is highly helpful for the very early diagnosis of various disorders, especially in cancer. Thus, for the treatment and management of various disorders, nuclear medicine has a very crucial role.

Another very important role it plays is in ‘therapeutic’ nuclear medicine. An example is seen in radioiodine[ I-131], which has been used since the 1950s for the assessment, imaging and treatment of goiter, thyroid nodules and thyroid cancer, producing remarkable results.

There are many other radionuclides like Phosphorus-32, Samarium-153, etc., which are used in therapy for pain palliation in cancer patients when the cancer has spread to the bone; to control pain it is given orally/intravenously, and it also prevents the continuous use of high potency pain killers which leads to harmful side effects. Thus, nuclear medicine provides a good quality of life for cancer patients.

There are many other radionuclides available for therapy in various disorders and also in various types of cancer.

Nuclear Medicine in South Korea

Korea has long history of nuclear medicine. The first Korean Society of Nuclear Medicine [KSNM] was formed on December 28th, 1961. Currently nuclear medicine in Korea has achieved great advances both in infrastructure and manpower. There are 159 PET scanners here, and the first clinical application of radioiodine [I -131] in thyroid disorders in South Korea started in 1959, in Seoul National University Hospital [SNUH] in Seoul.

The first radioisotope clinic was inaugurated in 1960, also at SNUH with the introduction of dot scanners (scintillation counters) for imaging in the year 1961, which were the predecessors of the present gamma camera, or PET/CT scanners.

Other milestones include the year 1969, when the first gamma camera was started in SNUH in the radioisotope clinic. The invitro labs for the blood measurement of thyroid function tests was started in 1975 in the radioisotope clinic.

In 1978, an independent Department of Nuclear Medicine was started in SNUH in the same year SNUH became an independent institute and also started the o99/ Tc99m [molybednum-technetium] generators for the production of 99m-Tc [technetium] isotope, which is used to label kits for the different scans of various parts of the body.

Radioimmunoassays [RIA] were started at SNUH and also for outside hospital and clinics in South Korea from 1980. From 1986, SPECT [single photon emission computed tomography], a dual head gamma camera, was introduced, especially for brain and cardiac imaging, along with the imaging of various other organs and parts of the body. In 1991, a nuclear medicine lab was opened in Boramae Hospital, renamed in 2008 as Seoul National University Boramae Medical Center. In 1994 the first PET scanner was installed in SNUH and in the following year a 13 MeV medical cyclotron was also installed.

Further advancement occurred with the starting of the first PET-CT scanner in SNUH in the year 2003. In the same year, SNUH started a branch hospital known as Healthcare system Gangnam Center and a PET-CT scanner was introduced there in the same year.

In 2008, another cyclotron was started at Seoul National University Bundang Hospital and in the same year another milestone was achieved with the opening of a Nuclear Medicine Department at Seoul National University’s Boramae Medical Center. In the same year an 18MeV cyclotron was installed exclusively for research purposes in the Biomedical Science Building in SNUH. The bioluminescence imaging system and an optical imaging system were introduced in 2006 and 2008 for animal research in SNUH.

In 2008 an animal SPECT-CT scanner was installed in Seoul National University’s Bundang Hospital.

In the year 2009, an animal PET/CT exclusively for animal imaging and research was installed at SNUH. This led to the introduction of the latest research in molecular imaging and multimodality nuclear imaging. Presently South Korea is at the forefront of nuclear medicine technologies, both in human and animal research, as well as for the treatment and diagnoses of various disorders of various parts of the human body. There are many nuclear medicine centers in various government and private hospitals and medical universities here.

Future Of Nuclear Medicine In South Korea

The future of nuclear medicine in Korea looks very bright, with the government investing in this branch of medicine extensively, knowing full well its importance in the early detection of disease, management and follow up of patients in various disorders, especially cancer.

Korea is expected to have a fully operational 100 MeV accelerator, exclusively for the use of radioisotopes for nuclear medicine, by the end of 2012. By 2016, the start of a radioisotope production cyclotron for the exclusive use of nuclear medicine departments in South Korea is expected.

Nuclear medicine is rightly called as “molecular nuclear medicine”, as it identifies the normal and abnormal regional molecular processes in the different organs of the body, while radiology is the structural imaging of the body using CT, X-ray, MRI and ultrasound.

With the advent of hybrid /fusion scanners like PET with CT [computed tomography] of radiology, called PET/CT scanners, and now with the latest technological advancement of PET fusion cameras with MRI of radiology, PET-MRI scanners, this is the beginning of an era of fusion imaging of anatomy with molecular imaging.